[libata] kill ata_sg_is_last()
Short term, this works around a bug introduced by early sg-chaining work. Long term, removing this function eliminates a branch from a hot path loop in each scatter/gather table build. Also, as this code demonstrates, we don't need to _track_ the end of the s/g list, as long as we mark it in some way. And doing so programatically is nice. So its a useful cleanup, regardless of its short term effects. Based conceptually on a quick patch by Jens Axboe. Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
This commit is contained in:
@@ -5134,6 +5134,7 @@ static void ipr_build_ata_ioadl(struct ipr_cmnd *ipr_cmd,
|
||||
u32 ioadl_flags = 0;
|
||||
struct ipr_ioarcb *ioarcb = &ipr_cmd->ioarcb;
|
||||
struct ipr_ioadl_desc *ioadl = ipr_cmd->ioadl;
|
||||
struct ipr_ioadl_desc *last_ioadl = NULL;
|
||||
int len = qc->nbytes + qc->pad_len;
|
||||
struct scatterlist *sg;
|
||||
|
||||
@@ -5156,11 +5157,13 @@ static void ipr_build_ata_ioadl(struct ipr_cmnd *ipr_cmd,
|
||||
ata_for_each_sg(sg, qc) {
|
||||
ioadl->flags_and_data_len = cpu_to_be32(ioadl_flags | sg_dma_len(sg));
|
||||
ioadl->address = cpu_to_be32(sg_dma_address(sg));
|
||||
if (ata_sg_is_last(sg, qc))
|
||||
ioadl->flags_and_data_len |= cpu_to_be32(IPR_IOADL_FLAGS_LAST);
|
||||
else
|
||||
ioadl++;
|
||||
|
||||
last_ioadl = ioadl;
|
||||
ioadl++;
|
||||
}
|
||||
|
||||
if (likely(last_ioadl))
|
||||
last_ioadl->flags_and_data_len |= cpu_to_be32(IPR_IOADL_FLAGS_LAST);
|
||||
}
|
||||
|
||||
/**
|
||||
|
Reference in New Issue
Block a user